


Arithmancy For Beginners

by Minnow_53



Category: Harry Potter - J. K. Rowling
Genre: Fluff and Humor, M/M, Marauders Era (Harry Potter), Not actually about maths, Romantic Fluff
Language: English
Status: Completed
Published: 2020-08-22
Updated: 2020-08-22
Packaged: 2021-03-06 16:00:59
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,635
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26041594
Author URL: https://archiveofourown.org/users/Minnow_53/pseuds/Minnow_53
Summary: One and one makes two, but sometimes three gets in the way.  Remus + Sirius = fluffy Marauder-era fic.
Relationships: Sirius Black/Remus Lupin
Kudos: 20





	Arithmancy For Beginners

**Author's Note:**

> First published on LiveJournal 16/5/07.

The quotes at the start of each section are from _First Steps In Arithmancy_ by Pythagoras Crouch.

_The singular one is the core of all magic. With one wand we cast our spells; with one will we project our desires on to the universe. How great is one! Without this number, the structure of the Wizarding world would crumble into oblivion_.

One may be a fine, upstanding number at the very heart of Arithmancy, but Remus and Sirius are, inappropriately, in two minds about it. 

To Remus, one stands for the lonely little boy who wandered out to see if he could find another little boy to play with but met a wolf instead. One means being on your own when your limbs stretch and bend so painfully every full moon: even with all your friends around you, there are certain things you have to endure alone.

One also reminds him of his first year at Hogwarts, and the day he had to Transfigure a dead bee into a chunk of amber all by himself, because he was the only person in the class without a partner. He stared at his bee for ten minutes, occasionally glancing round shyly at the other students to see how they were getting on. Even Peter Pettigrew, paired with a blond boy Remus didn’t know, had managed a very creditable stone with a honeycomb pattern at the centre. As for Black and Potter’s symmetrical, translucent sphere, Professor McGonagall held it up for the whole class to see. ‘Look how they’ve kept the bee suspended in the resin. Ten points to Gryffindor!’ 

Remus tried to emulate their work, bee and all, muttering ‘Swish, flick and bend’ to himself as he grimly wrestled with the difficult exercise. The bee seemed to stir, rather sluggishly, and dutifully turned itself into a sludgy, grubby, orange mass with a forlorn pair of broken wings trapped inside it.

McGonagall was most understanding, and chirped, ‘I think that’s excellent in the circumstances, Lupin.’ She even patted him on the head, which earned him a loud whisper of ‘Teacher’s pet!’ from Pettigrew’s partner. But Remus felt so frustrated that it took all his willpower not to smash the container full of dead bees and lie on the ground kicking and screaming in a childish tantrum. Even now, years later, when he works with Sirius and is in the top five at Transfiguration, he still goes hot all over when he remembers that dreadful lesson.

Sirius, on the other hand, finds the number one nostalgic. ‘I can remember right back to when I was born,’ he claims, though his friends are a bit sceptical. ‘That’s impossible!’ Peter always retorts, earning himself a thump. 

Impossible or not, to Sirius, one represents a spoilt little boy, whose mother crouched on the floor with him and played Gobstones. Walburga Black was the Slytherin champion at Hogwarts, unbeaten for a whole seven years. But she always let her son win: even though he was only a baby, even though he could hardly stammer ‘Godtone’, the pieces were invariably charmed in his favour. Every time Walburga lost, she would sigh ruefully and say, ‘What a clever boy!’ and roll him over and tickle him till he chortled and squealed.

One, to Sirius, is the world before Regulus came, before his mother stopped smiling and singing lullabies to him – or, indeed, singing at all – and shut herself in her room to weep. One is being lifted high in the air by his father and paraded round the room in front of all the relatives, to coos and gurgles and smiles. One is a prince, a darling, a child who, in his first eighteen months, laughed a lot more often than he cried. One, which only Remus knows about, is a Little Lord Fauntleroy suit of blue with a white, lacy collar, in which Sirius was photographed just before his second birthday, held tightly in his beaming mother’s arms. 

*

_No number is more effective than two for easing Transfiguration. The most recalcitrant hamster or turtle will be lulled by two, and transform safely into a goblet, or sponge, or whatever you choose. Weather charms also rely on two, as does imitative magic, such as Polyjuice Potion._

Arithmancy aside, the perfect, quintessential two is, of course, the pairing of Remus and Sirius. If you want to be metaphysical about it, you could say that two is actually one, because for the past year and a bit Remus and Sirius have been pretty well inseparable. 

Two began on a rainy autumn day in Sixth Year, after a number of mysterious occurrences. A bag of Ice Mice suddenly appeared in Remus’s trunk one evening. Sirius, who had completely forgotten to do some urgent Charms coursework, found a three-foot essay on wand-movements under his pillow, flawlessly rendered in his own handwriting. In Muggle Studies, Remus received a note saying, _‘Meet me by the Whomping Willow after school_ ’ to which he replied _‘When I’ve done my homework’_. In this way, the pairing was forged.

Remus used a Beautifying Charm to transform the upstairs room of the Shack into a golden bower of candlelight, with a roaring fire in the grate and rich hangings on the bed, and Sirius produced half a bottle of Firewhisky. They even managed to ignore the stormy weather and the sound of raindrops splattering against the grubby windows, though Sirius listened for a minute and said, ‘I can hear a bird singing.’ 

‘Maybe it’s an Augurey, and we’re going to die,’ Remus said, shivering a bit and moving closer to the fire. 

‘No, I think it’s a phoenix,’ Sirius said after some consideration, much to Remus’s relief. 

During the wettest November on record, Remus and Sirius spent a lot of time outdoors, slipping away from their friends to meet in the Hogsmeade woods. As they kissed hungrily under the trees, rain dripped on to their heads and eyelashes, trickling down their faces and the back of their necks. But Sirius would gaze into Remus’s eyes and Remus would gaze back; and though their clothes and hair were drenched, for all they noticed, they might as well have been enclosed in a Bubble Charm. 

They used to come back to Gryffindor Tower soaked to the skin. ‘You’re getting water all over the floor!’ Peter said, astonished. ‘Didn’t you do an Impervius?’

‘Why would we need one?’ Sirius said, genuinely bewildered. ‘It’s a beautiful day.’

By some miracle, James and Peter still don’t actually know about the two thing, and both Remus and Sirius want it to stay that way. James can be a bit funny about boys who like other boys: there was that guy with frilly dress-robes in Fifth Year, and James called him ‘queer’ and refused to have him in the Quidditch team. No doubt Peter would follow James’s example, though he might not understand all the ramifications of the relationship. 

*

 _Three is the most magical of all numbers, and its use is so widespread that I hardly need to provide many examples. I am sure that the lowliest student of Arithmancy will know that three is the traditional number for wishes. And, of course, three is compulsory in the sealing of Unbreakable Vows and the calibration of a timeturner._

This ‘most magical’ of numbers isn’t all good news. For a start, three can never be divided in any satisfactory fashion, because one part always gets left out. And even in Wizarding mathematics, three is a triangle – sharp, angular, and potentially painful. At this point in Seventh Year, three represents Remus, Sirius and James, with Sirius at the centre, if a triangle can be said to have a centre: at the apex, if you like.

James loves Sirius, in a manly, English, best mate, stiff-upper-lip, heterosexual way. Since becoming Head Boy, he’s taken to crawling into Sirius’s bed when he can’t sleep for thinking about Lily. ‘She’s agreed to come to a Christmas party with me,’ he tells Sirius as they snuggle under the covers in the dark. ‘I’m actually going to be seeing her over the holidays!’

The first time James sought out Sirius at night, Remus had just climbed into Sirius’s bed. He was reaching over to kiss him awake, when the curtains parted on the other side, and someone shoved in a glowing wand.

‘Hey, Padfoot,’ James whispered, and Remus gave an involuntary yelp.

James scrambled down, his hair wilder than ever. ‘What are _you_ doing here, Moony?’ he asked, and then went bright red, the dim light giving him the look of an overripe tomato. 

There was an undignified tussle as Remus tried to extricate himself: Sirius had flung both legs across him, and was lying there shaking with laughter, apparently unable to move.

‘Sirius, let me out,’ hissed Remus, but Sirius just clutched him and laughed harder than ever. 

‘You’re mad, you know that?’ Remus said, loudly enough to wake Peter, who called out in a sleepy voice, ‘Wha’s going on?’

‘Nothing,’ said James, obviously secure in his Merlin-given right to first claim on his best mate. He held back the curtain, his wand trained on Sirius, whose face was hidden in the pillow, shoulders still shaking. 

‘C’mon, Padfoot! Remus is just going, aren’t you, Moony?’ James, in his blue and white striped pyjamas, looked puzzled and innocent, and Remus didn’t have the heart to challenge him.

Instead, he shoved Sirius aside, rather too hard, and managed to free himself. Sirius stopped laughing and said ‘Ouch!’ and Remus returned to his own four-poster without a backward glance, though he did hear James saying, ‘So what was Moony doing in your bed?’ 

‘Last minute revision for our Muggle Studies test. He forgot what a doctor was.’ 

Since then, Sirius has had to sneak into Remus’s bed, which isn’t an entirely satisfactory arrangement. James is unpredictable at the moment, sometimes staying down in the common room with Lily Evans until way after bedtime. Sirius will be just about to nip over to Remus when James will burst into the dormitory, eager to analyse every detail of how Lily won’t say she loves him though he says he loves her, and does it mean she’s not really committed like he is? 

On those nights, Remus waits alone, a bit disgruntled, for Sirius to turf James out. If he leaves before midnight, there’s a good chance that Sirius will soon be pulling back the bedclothes and whispering, ‘Are you awake, Moony?’ The downside is that Sirius is likely to waste twenty minutes complaining about James bending his ear in the first place. But Remus puts up with it patiently enough, until Sirius runs out of steam and starts to concentrate on him instead. 

*

 _I cannot sing the praises of four too highly. Four is, quite literally, the cornerstone of magical theory. Without four, we would have no building spells, and we would be forced to live like Muggles, in horrid little houses that we couldn’t extend or transform. Four provides the basis for domestic magic, such as cleaning spells, cooking charms, and all that is practical in the Wizarding world._

In everyday life, four is the Marauders, of course. Though they’re now divided rather awkwardly into two, one and one (or even a half, as Sirius meanly says when Peter hasn’t pulled his weight), they still exist as an entity. James, still unaware of the Remus/Sirius alliance, says ‘We’re like the Beatles,’ and Remus says, ‘But the Beatles split up.’

‘Oh. Lily didn’t tell me that,’ says James, looking, for a second, very young and crestfallen.

Four is also part of the inscription Sirius carved into his desk during History of Magic one cold Wednesday afternoon: ‘Moony + Padfoot 4ever’. It’s a cliché, he knows, but it makes him happy to see their names combined whenever he’s forced to sit through Binns’s lesson. He hasn’t told Remus about the carving, because Remus would worry. He’d say ‘What if James sees it and thinks it was me?’ And he’d have a point, because sentiment isn’t really Sirius’s thing. 

To help tune out Binns, Sirius has spent the past few lessons colouring in his handiwork, without using his wand. Not that he needs to: he has some very fancy magic crayons that his uncle sent him.

‘Goblins like to behead their victims extremely slowly,’ Binns drones, and Sirius, his attention caught, glances up from his colouring for a moment. Binns is perched on the edge of his dusty desk, looking almost as dusty himself, in his ghostly way. He glares round the classroom to make sure the students are paying attention. ‘They use a Rusty Saw Hex, derived from a Muggle practice of 1468. The saw is poised on the back of the neck, and slices through slowly.’

Lily Evans says, ‘Ew!’ and her best friend, Zoë Smith, giggles nervously. Binns, distracted, loses concentration and continues, ‘Of course, the fourteenth goblin revolution never really took place,’ and Sirius returns to his task. The ‘Moony’ is already orange and yellow, the ‘+’ a rather fine purple, and he now colours ‘Padfoot’ red, with a golden border. The crayon is charmed to shine dully, like real 22-carat gold, and Sirius worries for a moment that this will make his inscription a bit ostentatious: he doesn’t want the Slytherins to see and comment on it during their own History of Magic lesson, though of course they wouldn’t have a clue who Padfoot and Moony are.

‘A number of elves helped to build the citadel,’ Binns says. ‘Can anyone tell me what it was called?’ No hands go up, and during the ensuing silence, Sirius decides that next week he’ll colour the ‘4’ green, perhaps with black stripes, unless he changes his mind in the meantime. 

*

_What can one say about five? It is certainly a pretty number, comprised of a curve and two straight lines. Classical Arithmancers claim that five has protective powers: the Imperius and Cruciatus curses can apparently be deflected by a pentagram, though there is no proof of this. It is worth noting that wizards in the south of England consider five the number of reconciliation._

Five is, in fact, rather hard to define all round, though most wizards concur that it has religious overtones and some vague link with Merlin. ‘That’s because it’s a prime number,’ Sirius explains to Peter, who looks confused and asks, ‘What’s a prime number?’

‘Wormtail, you’re an idiot! Any number that can’t be used in a hex or the Dark Arts.’

Sirius finds five a bit pointless. ‘It just sits there and doesn’t _do_ anything, Moony.’ But five to Remus evokes his favourite childhood books, the Fabulous Five, a group of four young witches and wizards with a pet Niffler, who go round solving mysteries. He’s outgrown the books, really, but still has the whole series tucked away in his trunk. It’s a comforting number to him, with a predictably happy outcome.

On nights when James keeps Sirius up till the small hours, he likes to imagine that he and his friends are solving mysteries around the school. He's currently trying to find out which of the Slytherins set the Quintaped free to terrorise the staff and pupils. He uses Padfoot as the Niffler, which means Lily has to join the humans to make up the numbers. Sirius does at least return to his usual form when the villains (Snape and Malfoy) are defeated and he and Remus are leaning in for a celebratory kiss.

Remus is actually a bit paranoid about Lily appearing in his daydreams. In real life, he could swear that she’s always watching him and Sirius with those clear, dispassionate green eyes. 

‘I bet she’ll tell Prongs about us, and then he’ll never talk to us again,’ he grumbles.

‘You say that like it would be a bad thing. He bent my ear for three hours last night, Moony! I’d welcome a bit of peace.'

Of course, five also equals the four Marauders plus Lily Evans, even if Remus isn't altogether happy about it. Typically of five, Lily’s presence in the group, though still rather tangential, has had a mixed effect.

James’s irrational demands on Sirius’s time are definitely a negative, or an arithmantical minus.

On the positive side, while five should technically be as divisive as three, it actually splits smoothly into Remus/Sirus and James, Lily and Peter. Far from being left out, Peter has taken on the role of squire to James’s knight, always around to reassure and support. Okay, James may not climb into Peter’s bed – ‘because that would be too weird,’ as Sirius says – but during the daylight hours he’s always at James’s side, attending him while he courts his lady, ready to pick up the pieces when things go wrong, as they so often do.

When Lily told James rather sharply that she needed a bit of time with her friends Zoe and Tabitha, Peter staunchly stayed with James all afternoon. He eventually persuaded him outside for a walk instead of glowering at the three girls as they giggled together in the common room. ‘They’re probably talking about James, anyway,’ Sirius remarked to Remus when the other two had left. 

*

_Six could be seen as the number of romance. Known to many Arithmancers as ‘sultry six’, the number is dominant in all forms of Entrancing Enchantments and is vital for the brewing of Amortentia. At the time of the first Goblin Rebellions, the numerical six (6) was used to represent a heart: this archaic practice still survives in rural Scotland._

To Remus and Sirius, six is a _good_ number, representing the most times they’ve had it off in one twenty-four hour period: actually, it was a nine-hour period in the spring term of Sixth Year, before their Saturdays together had become something of a comfortable routine. Hogwarts had, unusually, qualified for the inter-schools Quidditch tournament, and James was at Beauxbatons for the weekend. Only the team were allowed to go, so Peter was disconsolate. He eyed the empty seat next to his at breakfast, listlessly poking at the yolk of his fried egg until it was a runny mess.

‘Why don’t you just pretend he’s here?’ snapped Sirius in the end, after Peter had sighed deeply for the tenth time. ‘Look, give him some food.’ He pushed a plate over to James’s place, and piled it with bacon, mushrooms and sausages. ‘There, Prongs,’ he said to the empty chair, ‘enjoy your breakfast. Oh. Don’t you like mushrooms?’

He cocked his head to the side for a minute, pretending to listen intently. ‘Right. Sorry, mate. I’ll have them.’ He spooned the mushrooms on to his own plate. ‘Mmm. You don’t know what you’re missing, Potter.’

Peter didn’t quite burst into tears, but he did flounce away from the table in a huff, tossing his head so ostentatiously that Sirius remarked, ‘D’you ever wonder if Peter could be, well, one of _us_ , Moony?’

‘He has a girlfriend,’ Remus said.

‘Well, so did I,’ Sirius said. ‘I mean, I was friends with her anyway.’

On this occasion, having been plunged in despair at having to put up with Peter all weekend and miss their time in the Shack, Sirius was elated at his absence. ‘But we really should go and look for him,’ Remus said.

‘Why? If he’s pissed off, that’s his problem. You know we won’t get away next weekend, because we have to go to Hogsmeade. Come on, Remus.’

Remus should have felt guilty at capitulating so easily, but once they got to the Shack he didn’t even think of Peter for the next few hours; indeed, nothing could have been further from his mind.

On the bed, entangled in each other’s limbs, they agreed that the Shack looked lovely on an April morning, with the plane tree outside just coming into leaf, and green, dappled light falling on their naked bodies. 

‘Your hair isn’t really black,’ Remus said. ‘There’s a lot of gold in it.’

‘More gold in yours,’ said Sirius, pushing back Remus’s fringe, and contemplating him thoughtfully. ‘Your eyes are sort of gold too, sometimes.’

‘They’re brown,’ Remus protested, but it was easier to give in than to argue, so he kissed Sirius back instead. 

‘We forgot the charm,’ Sirius said, surprised, after the fifth round, contemplating the faded wallpaper, peeling in strips from the wall, the fireplace choked with cankers, the filthy bedspread. ‘Funny, I didn’t notice earlier. That bloody mattress keeps stabbing me, too. I think there’s a broken spring.’

‘Maybe we didn’t need the charm today,’ Remus said. ‘I know that spring! Why d’you think I always choose the side nearest the window? There’s a creaky patch there too.’

‘You sod!’ Sirius wrestled Remus over to the spring, and in the process got distracted, though not so distracted that he didn’t immediately say triumphantly, ‘Six times! That’s not bad. We only ever managed five before.’

‘I wonder how long that took,’ Remus said, fishing his watch out of the pockets of his discarded robe. ‘Right. We got here at nine, so that’s about once every hour and twenty minutes.’

Sirius said, ‘I’d have thought we could have done a bit better. It’s a pity you insisted on going to sleep for such ages. Shall we see if we can make up for it?’

‘No, we can’t. It’s already dinner time, and Wormtail’s going to be suicidal if we’re not there.’

‘It’s his own fault,’ said Sirius, but he nevertheless followed Remus back to the castle without a word of complaint. 

Peter, in the event, spent the evening babbling about how he’d spent all day in the company of his Hufflepuff friends, playing Hide and Seek in the empty classrooms, and hadn’t apparently missed Remus and Sirius at all. In fact, he was in high spirits at dinner, and ate three helpings of pudding.

‘Shame,’ Sirius said. ‘If we’d known, we could have gone for the seven.’ 

Though they’ve often tried in the months since at least to equal their record, they haven’t managed it yet, mainly because they’ve rarely had more than two or three hours alone. Recently, James has been finding Peter's constant presence a bit irksome, and he's taken to using his two-way mirror to summon Sirius from the Shack when Lily isn’t around and he’s feeling bored and lonely: as always, when James calls, Sirius finds it hard not to answer.

‘Don’t bring your damn mirror with you,’ Remus often says, exasperated, and Sirius replies, ‘If I don’t, he’ll begin to suspect there’s something going on between us.’

‘Well, there is.’

‘But he might want to tell me something important.’ 

‘Of course he won’t. He wants to tell you that Evans has abandoned him in favour of the library, and does that mean their love is dead, and what’s he going to do till he sees her again?’

But Sirius always answers anyway, even though he does sometimes wonder how Prongs would feel if he started summoning him to talk about his relationship with Remus. ‘I could tell him that you refused to come up to the dorm with me at break,’ Sirius says, and Remus says, ‘I didn’t refuse!’ and Sirius perks up and says, ‘Let’s go, then!’ and they both forget about James altogether. 

*

 _The Arithmantical seven is used primarily in healing and household charms. The design of St. Mungo’s Hospital is based on seven, as are all healing outlets throughout Wizarding Britain. A few Arithmancers still believe that if a Wizarding family produces seven sons, at least one will be a Squib: this may be a superstition, but it has caused many purebloods to limit their progeny._

At the moment, seven means Seventh Year and hard work, which none of the Marauders find especially healing. Both Remus and Sirius are doing seven NEWTs: Charms, Transfiguration, Defence Against the Dark Arts, Muggle Studies, Arithmancy, Potions and Divination. They’re also doing the OWL/NEWT in History of Magic, but everyone has to take that, so it doesn’t count.

James hates Divination, as his son also will some day, so he’s opted for Care of Magical Creatures instead, with an eye to becoming a vet. Peter’s doing it too, possibly with an eye to becoming James’s assistant.

‘Prongs really _is_ very good with animals,’ Remus says. ‘When I transform, he always has a sort of calming effect.’

‘So Padfoot doesn’t?’ Sirius asks, hurt.

‘Well, I love Padfoot, but he just wants to play, doesn’t he?’ Remus says tactfully. ‘Prongs has a quiet, stag-like authority.’

‘I thought you could never remember being a wolf,’ says Sirius, in a rather grumpy tone.

Remus does remember the several occasions when he’s come to and seen the stag masterfully nudging a whining dog away from him. Much as he likes Padfoot, the dog can be a bit annoying when Remus is feeling sore and miserable and it starts begging him relentlessly to get up and throw a stick for it or something.

Seven is also the number of potions Remus regularly has to take after the full moon, besides being smothered in Murtlap essence. These include painkillers, anti-scarring agents, blood replenishers, and Prozackia, a mild antidepressant invented by a famous werewolf of the eighteenth century: _‘for one may become sadly distraughte of minde, when one transformeth everye month.’_ This is Remus’s favourite, because it has much the same effect as a Cheering Charm.

‘It’s not really quite decent, you being so giggly the day after the transformation,’ Sirius has remarked more than once, rather put out. He’s exhausted after the sleepless night, and is getting a cold, because Padfoot always insists on diving into any random puddle or stream. The Hospital Wing is cosy, with the curtains drawn across the high windows, and flickering yellow lamps casting a soft light over the bedclothes, but Sirius has to venture outside in a minute to fetch James from Quidditch practice. He may not want to be a werewolf as such, but he’s nevertheless a bit jealous of Remus, tucked up snugly in bed. He snatches the empty Prozackia tumbler from the bedside table and runs his index finger round the inside, to scrape out any remaining dregs of the wonderful potion.

‘That’s so unhygienic,’ Remus says. ‘You’re disgusting, Padfoot.’

‘I want to be happy too,’ Sirius grumbles, sucking his finger so hard Remus worries it might fall off.

‘Is it working?’

Sirius considers. ‘No. Next time, tell Pomfrey to give you a double dose.’ He gets up gloomily and trudges out of the Hospital Wing, down the stairs and into the cold evening, suddenly feeling the urge to run and whoop all the way to the Quidditch pitch. 

*

_Occasionally, random numbers acquire an empirical significance in Arithmancy: fifteen and seventeen, for example, have proved auspicious for brewing simple Ageing Potions. Numbers that occur in Divination or in dreams may have some deep meaning; or, conversely, they may mean absolutely nothing at all._

Divination isn’t an exact science, but Sirius regularly sees numbers floating about in his crystal ball. The number twelve often appears, a persistent twelve that won’t go away; and though he isn’t superstitious about it – a twelve isn’t a thirteen, after all – he doesn’t like the sight of it hanging there, black and spindly, like bars on a window. 

Remus claims to have seen a hundred and thirty-six in his tea-leaves, but has no idea what it means. ‘Maybe it’s the age I’ll live to,’ he says, though of course it’s laughable to think of a werewolf surviving for so long. ‘Or maybe it’s the number of years we’ll be together.’

‘That gives us a hundred and thirty-four and a half more,’ says Sirius. For some reason, the thought pleases him immensely, and when they sneak out that Saturday he accidentally-on-purpose leaves his two-way mirror behind. 

**End**


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